The present invention relates to a process for the preparation of 2-hydroxy-4-(hydroxyalkoxy)-benzophenone. More particularly the present invention is concerned with a method for oxyalkylating 2,4-dihydroxybenzophenone in the presence of water using a basic catalyst.
It is well known that compounds such as those produced by the process of Applicant's present invention may be used as ultraviolet light absorbers and are particularly useful as light-stabilizers in resinous compositions.
Various synthesis schemes for making the subject compound have been disclosed in the literature. Applicant's co-pending U.S. Pat. application, No. 197,042, now U.S. Pat. No. 4,885,396, discloses a method of preparing the subject compound, wherein the 2,4dihydroxybenzophenone is reacted with ethylene carbonate in the presence of a quaternary ammonium salt catalyst, at temperatures preferably between 140.degree. C. to about 175.degree. C. The reaction may also be carried out in an organic solvent which is inert to the reactants but it is preferably carried out in the absence of any solvent.
Eggensperger discloses in U.S. Pat. No. 3,676,471 a method of preparing 2-hydroxy-4-(hydroxyethoxy)benzophenone by reacting the dihydroxybenzophenone with ethylene carbonate or ethylene oxide in an organic solvent, in the presence of a basic catalyst preferably alkali carbonates, alkaline earth carbonates, or alkali alcoholates. This method has a number of disadvantages. It requires the use of solvents, particularly ketones. Because of the basic nature of the reaction mixture only substantially inert ketones may be employed. Further, Example 1 discloses that the reaction product is obtained by extraction with a chlorinated hydrocarbon. Halogenated hydrocarbons present problems because they are toxic and potential environmental hazards.